How to Verify Radon Licenses and Certifications

This is the part of the process most homeowners skip. It takes about 30 seconds per contractor and protects you from hiring someone who is either unlicensed, has had their license suspended, or has open complaints. This page walks through every step.

Before you can verify anything, you need three pieces of information from each contractor you're considering:

• Full legal business name. Not just the marketing name.
• DORA radon mitigation license number. Should be on the quote, on the business card, or available on request.
• NRPP or NRSB certification number. Same — should be readily available.

If a contractor hesitates or won't provide these on request, that's a red flag in itself. Reputable Colorado mitigators put both numbers on every quote.

Colorado DORA maintains a public license lookup. The process:

1. Go to apps.colorado.gov/dora/licensing/Lookup/LicenseLookup.aspx.
2. In the search form, select the profession type. Radon mitigation is under "Office of Radon Professionals" — you may need to scroll or search for "radon."
3. Enter the contractor's business name or license number.
4. Click search.

The result page will show:

• License status. Should be "Active." Inactive, expired, suspended, or revoked means do not hire.
• License number. Should match what the contractor provided.
• Issue and expiration dates. Active licenses are renewed periodically; expired licenses without renewal are a red flag.
• Any disciplinary actions. Public record. Open or recent actions warrant a follow-up question or a different contractor.

If the DORA lookup shows no record of the license number the contractor gave you, walk away. They're either lying about the license or made a typo — either way, you can't verify what doesn't exist.^[1]

NRPP and NRSB are separate national programs with separate lookups. Most Colorado contractors are certified through one or the other; some have both.

NRPP search

1. Go to nrpp.info/pro-search.
2. Search by name, ZIP code, or certification number.
3. Verify the certification type matches what's needed. For mitigation, look for RMP (Radon Mitigation Provider) or RMS (Radon Mitigation Specialist).
4. Verify the certification is current — not expired, suspended, or revoked.

NRSB search

1. Go to nrsb.org/for-professional.
2. Search by name, location, or certification number.
3. For mitigation, look for RRS (Residential Radon Mitigation Specialist) or RMS.
4. Verify currency.

If a contractor claims an NRPP or NRSB certification that doesn't show up in the public directory, that's the same kind of red flag as a missing DORA license. The certifications exist precisely so homeowners can verify them.^[2]

BBB isn't a licensing body, but it's a useful aggregator:

1. Go to bbb.org and search the contractor's name.
2. Look at the rating (A+ through F). Pay attention to the explanation, not just the letter.
3. Read the complaint summaries. Pattern matters: one or two complaints in a long history is normal; a series of similar complaints (poor workmanship, no-shows, billing disputes) is a pattern.
4. Read how the contractor responded to complaints. Quick, professional, and substantive responses are a positive signal; defensive, slow, or boilerplate ones are not.

Ask the contractor for proof of insurance. They should be able to provide a Certificate of Insurance (COI) showing:

• General liability: $1M minimum is industry standard.
• Workers' compensation: Required by Colorado law for employees.
• Coverage dates: Make sure the policy is current and will cover the install date.

The COI usually lists you (the homeowner) as a certificate holder or names your address as the work location. If the contractor declines to provide a COI, that's the same level of red flag as missing the DORA license.

Reviews on Google, Yelp, and Angi are valuable but selective. Tips for reading them well:

• Look at the contractor's response to negative reviews. Constructive, specific responses are positive signals.
• Search reviews for the words "warranty," "post-mitigation test," "still works," "5 years" — these surface long-term performance.
• Be skeptical of all-5-star ratings with no detail. Real customers leave detail.
• Cross-reference between platforms. A contractor with 5 stars on Google and 3.5 on Yelp may have a curated Google presence.